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Biomedical subjects

A G Reznikov

Publications and source records attributed to A G Reznikov.

At least 37 records · Page 2Linked to original sources
PubMed1986

[Functional state of the hypophysis and ovaries of rats with anovulatory syndrome during pharmacologic stimulation of dopaminergic receptors].

Pharmacological analysis of the role of hyperprolactinemia in the pathogenesis of anovulatory syndrome (AS) was performed in neonatally androgenized rats. Dopamine agonist, bromocriptine, administered to I or 2.5 month-old rats for 15 days decreased prolactin content in the adenohypophysis and partially normalized progesterone level in blood plasma. However, bromocriptine failed to prevent the development of AS or to interrupt persistent estrus in neonatally androgenized females. The results are in keeping with the concept on the leading role of hypothalamus noradrenergic insufficiency in the pathogenesis of experimental AS.

Animals↗
PubMed1983

It is possible that noradrenaline is the biogenic monoamine responsible for androgen-dependent sexual brain differentiation.

The effect of neonatal testosterone propionate (TP) treatment and its combination with alpha-methyl-p-tyrosine (alpha MPT) on noradrenaline, dopamine and serotonin contents in the hypothalamus of 7-day-old female rats has been studied. The property of alpha MPT to prevent anovulatory sterility in neonatally androgenized rats earlier established by the authors is related to interfering with a rise of hypothalamic level of noradrenaline induced by TP in the early postnatal period. The experimental data give evidence against the participation of dopamine in sexual differentiation of the brain and indicate the secondary character of serotonin content changes in the hypothalamus in relation to the noradrenaline level. Hence, noradrenaline may participate in androgen-dependent sexual differentiation of the hypothalamus.

Androgens↗
PubMed1979

[Participation of the hypothalamus in the pituitary and testicular responses to administration of the antiandrogen 4-nitro-3-trifluoro-methylisobutyranilide].

The effect of the antiandrogen 4-nitro-3-trifluoro-methylisobutyranilide (flutamide, NFBA) on the content of follitropine, lutropine and testosteron in the blood plasma as well as on the testicular activity of the steroid delta 5-3 beta-Ol-dehydrogenase (SD) has been studied in male rats with intact and destroyed hypothalamic median eminence. In sham-operated rats with intact hypothalamus the levels of lutropin, follitropin, testosteron and the enzymatic activity were 5, 2, 4 and 3-4 times as increased, respectively, under the effect of NFBA. After destroyal of the hypothalamic median eminence NFBA treatment did not change follitropin secretion, while lutropin, testosteron plasma levels and SD activity were only 1 1/2-2 times higher, i.e. significantly less as compared to those in sham-operated animals. The data obtained suggest the most important role of the hypothalamus in pituitary and testicular responses to NFBA administration.

3-Hydroxysteroid Dehydrogenases↗
PubMed1979

New evidences for participation of biogenic monoamines in androgen-dependent sexual differentiation of hypothalamic control of gonadotropin secretion in rats.

Corpora lutea have been found in the ovarian tissue transplanted into the anterior ocular chamber of castrated two-month-old male rats receiving on 3rd through 7th post-natal days alpha-methyl-p-tyrosine or p-chlorophenylalanine. Administration of these agents in combination with testosterone propionate to newborn female rats prevented essentially development of the anovulatory syndrome and maintained a normal picture of vaginal smears, ovarian and uterine structure as well as cyclic changes of adenohypophyseal and blood plasma lutropin contents and normal levels of estradiol and progesterone in the blood plasma except of progesterone level in animals receiving alpha-methyl-p-tyrosine. The preventive effect of the adrenoblocking agents droperidol and propranolol was weak and inconstant. Results suggest participation of catecholamines and serotonin in the androgen-dependent sexual differentiation of the brain in rats.

Animals↗
PubMed1978

Hypothalamo-hypophyseal-gonadal system in male rats and guinea pigs treated with the antiandrogen 4-nitro-3-trifluoromethylisobutyranilide.

Influence of the competitive testosterone antagonist 4-nitro-3-trifluoromethylisobutyranilide (NFBA) on the hypothalamo-hypophyseal-gonadal system in male Wistar rats and guinea pigs was studied. NFBA as well as nonlabelled testosterone diminished 3H-testosterone uptake in hypothalamus and hypophysis of castrated animals. Increase of plasma testosterone level was obtained after the antiandrogen treatment in a dose of 10 or 25 mg/kg per os during 3, 10 and 48 days. Maximal level of the hormone was noticed on the 10th day. The contents of 17-ketosteroids in testes had not changed, but the testosterone content and steroid-delta5-3beta-ol-dehydrogenase activity were high during the treatment period. After 10 days of NFBA administration increased plasma LH level was found. Increase in size and number of gonadotropocytes was revealed by histological and histochemical methods as well as Leydig cell hypertrophy. High plasma testosterone level and Leydig cell activation were obtained in guinea pigs as a result of NFBA subcutaneous injections in a dose of 10 mg/kg during 30 days. The suggestion is made that prolonged NFBA treatment produces changes in the testosterone metabolism. Short-term administration of NFBA may be used for the estimation of the hypothalamo-hypophyseal functional abilities.

Anilides↗
PubMed1976

[Effect of neonatal androgenization on biogenic monoamines of the hypothalamus and the functional activity of the rat pituitary].

Injection of testosterone-propionate to female Wistar rats on the 2nd--4th days of birth failed to alter the serotonin level, but produced a sharp fall of the noradrenaline and dopamine levels in the hypothalamus of 3 1/2-month-old animals. This was accompanied by an increase in the prolactin content in the adenohypophysis with the retention of the normal somatotropic activity. The results of these studied indicated the participation of catecholamines in the pathogenesis of the anovular sterility, and elucidated current views on the control of the hypophysial gonadotropic function.

Animals↗
PubMedDate not supplied

Prenatal stress and glucocorticoid effects on the developing gender-related brain.

Hormonal and neurotransmitter environment of nondifferentiated cells in the developing brain determines many of gender-specific behavioural and neuroendocrine functions. Early postnatal and long-term effects of maternal stress or prenatal glucocorticoid on sex-related peculiarities of the brain morphology, biogenic monoamine turnover, testosterone metabolism, hypothalamic noradrenaline (NA) and adrenocortical responses to an acute stress were studied in Wistar rat offsprings. Maternal stress (1 h immobilization daily for gestational days 15-21) prevented development of sexual dimorphism in neuronal cell nuclei volumes in suprachiazmatic nucleus (SCN) in 10 day old pups. That was associated with a disappearance of male female differences in NA and 5-hydroxytryptamine turnover in the preoptic area (POA) and dopamine (DA) turnover in the mediobasal hypothalamus (MBH) by decreasing them in male pups. Hydrocortisone acetate (5 mg daily during the last week of pregnancy) produced changes in NA turnover in the POA of males and females which were quite similar to those after maternal stress. Changes in aromatase and 5alpha-reductase activities in the POA of male pups were quite opposite as affected by maternal stress or prenatal glucocorticoid. Sexual differences in 5alpha-reductase activity in the MBH appeared due to its increase in prenatally stressed male pups. In contrast to adult males, in adult females maternal stress did not restrict hypothalamic NA and blood plasma corticosterone response to acute stress (1 h immobilization). Our findings on morphology and functions of gender-related developing brain areas stand in correlation with modifying effects of maternal stress and prenatal glucocorticoid on behavior and neuroendocrine regulations.

Adrenal Glands↗
PubMedDate not supplied

Early and long-term neuroendocrine effects of prenatal stress in male and female rats.

The effects of maternal stress, termed prenatal stress (PNS) on the neuroendocrine regulation of reproduction and the stress reactivity of offspring were studied in rats. PNS prevented the formation of sexual dimorphism in catecholamine levels, aromatase activity, and androgen 5alpha-reductase activity in the preoptic area of the brain and the mediobasal hypothalamus in 10-day-old rats. The morphological correlate of the functional lesions induced by PNS consisted of the elimination of gender-related differences in the volumes of neuron nuclei in the suprachiasmatic nucleus. Prenatal stress altered the stress and adrenergic reactivities of the hypothalamo-hypophyseal-adrenal system in mature males and females. The long-term effects of PNS were regarded as a consequence of the disruption of the hormone-neurotransmitter imprinting of the neuroendocrine system.

Animals↗